Creating Empathy Maps is useful for synthesizing research data in order to better understand the users. Empathy Maps are great for creating Personas, identifying users with different mindsets.
Picking a font size for the web used to be really easy. 16 points and you’re done. You could feel confident that your content would be decently readable on PC or Mac, Netscape or IE. Man, have times changed.
Typography
What's the Best Font Size For the web? Well, It Depends… — Imarc